# buoyancy flows in open air courtyard

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 May 6, 2008, 10:32 buoyancy flows in open air courtyard #1 Raha Ernest Guest   Posts: n/a I have modelled a simple open space, a kind of courtyard between buildings, and would like to the effect of solar radiation and particularly the buoyancy flow of air when flux of heat from the open space boundaries radiates back into the space. I do not want to introduce airflow from anywhere, and would like to assume a still/calm/ or 0m/s context and observe buoyancy flows. I have used Gambit to make a 15x15x10m cube and extracted the inner 12x12x9m to create this open to air courtyard. I have then enclosed it within a 240x165x100m domain. Meshed everything, export to Fluent, open it in fluent, checked the grid. I tried to specify everything to my knowledge and the solution wouldn't do iterations. I don't know where I went wrong but here is few of the things I specified, DEFINE- MODELS, Solver Models (density based), Viscous Models (k-epsilon standard model, enhanced wall treatment, thermal effect), Radiation Model (Discrete Ordinance DO, DO Irradiance, Solar calculator, Sun direction vector, Longitude 5.9, latitude 37.50North, date 08/August 1500hours, illumination parameters-direct solar irradiation 900w/sq.m â€"diffuse solar irradiation 200w/sq.m), DEFINE-MATERIALS, Fluid-air, air at 40 deg.C (density= 1.127kg/cub.m), used boussinesq, beside reading the manual, had trouble defining other materials parameter like scattering and absorption coefficient, and couldn't be able to sort out piecewise-linear and polynomial for materials. DEFINE-OPERATING CONDITIONS, I checked/ticked gravity, boussinesq parameter â€" operating temperature (313.16K) = 40 deg.C. SOLVE-INITIALIZE, compute from all zones (didn't know whether I should compute from a face in the model or the face of the domain, velocity=0 on all x,y,z, and temperature = 313.16. Then when I click Iterate, nothing happens.

February 22, 2010, 07:50
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try to change Solver Models--density based to "pressure based"

Quote:
 Originally Posted by Raha Ernest ;150544 I have modelled a simple open space, a kind of courtyard between buildings, and would like to the effect of solar radiation and particularly the buoyancy flow of air when flux of heat from the open space boundaries radiates back into the space. I do not want to introduce airflow from anywhere, and would like to assume a still/calm/ or 0m/s context and observe buoyancy flows. I have used Gambit to make a 15x15x10m cube and extracted the inner 12x12x9m to create this open to air courtyard. I have then enclosed it within a 240x165x100m domain. Meshed everything, export to Fluent, open it in fluent, checked the grid. I tried to specify everything to my knowledge and the solution wouldn't do iterations. I don't know where I went wrong but here is few of the things I specified, DEFINE- MODELS, Solver Models (density based), Viscous Models (k-epsilon standard model, enhanced wall treatment, thermal effect), Radiation Model (Discrete Ordinance DO, DO Irradiance, Solar calculator, Sun direction vector, Longitude 5.9, latitude 37.50North, date 08/August 1500hours, illumination parameters-direct solar irradiation 900w/sq.m â€"diffuse solar irradiation 200w/sq.m), DEFINE-MATERIALS, Fluid-air, air at 40 deg.C (density= 1.127kg/cub.m), used boussinesq, beside reading the manual, had trouble defining other materials parameter like scattering and absorption coefficient, and couldn't be able to sort out piecewise-linear and polynomial for materials. DEFINE-OPERATING CONDITIONS, I checked/ticked gravity, boussinesq parameter â€" operating temperature (313.16K) = 40 deg.C. SOLVE-INITIALIZE, compute from all zones (didn't know whether I should compute from a face in the model or the face of the domain, velocity=0 on all x,y,z, and temperature = 313.16. Then when I click Iterate, nothing happens.